Contact making voltmeter



y 5, 1935- F. J. CHAMPLIN 2,039,632

CONTACT MAKING VOLTMETER Filed April lO, 1954 Inventor Franklin J. Champlin.

His Attorngg,

Patented May 5, 1936 UNITED STATES CONTACT MAKING VOLTMETER Franklin J. Champlin, Dalton, Masa, assignorto General Electric Company, a corporation of New York Application April 10, 1934, Serial No. 719,898 4 Claims. (01', zoo-104) My invention relates to contact making voltmeters, and more particularly to improvements in the mechanical construction of such devices.

A contact making voltmeter is anelectromagnetically operated voltage responsive circuit controller which is ordinarily used as a master voltage responsive element of voltage regulating systems ofthe motor operated type, such for example, as motor operated induction feeder regu- 1 lators, or motor operated transformer tap changing regulators. The operation is such that when the voltage is above normal a set of contacts on the meter close thereby completing a circuit to the motor which causes it to operate in such a direction as tocause the regulator to lower the voltage, whereas if the voltage is below the normal value a different set of contacts close thereby reversing the motor and causing the regulator to increase the voltage.

Heretofore, contact making voltmeters have been relatively crudely constructed and have consisted essentially of a base member on which are individually mounted an operating solenoid magnet, a guide bracket for the core thereof, a

contact beam operated by the magnet and two stationary contacts for cooperation with the contact beam. Separate adjusting means have been provided for each of the stationary contacts. As a result of such construction, I have found that whenever the magnet, or the guide member, or the support for the contact beam is moved out of a predetermined adjustment the relative adjustment of all of these parts is adversely affected and the accuracy of the meter 5 is impaired. Furthermore, as each of the stationary contacts is separately adjustable, I-have found that in adjusting the voltage held by the contact making voltmeter, as well as in adjusting the voltage hand held by the regulating sys tom, the contact beam will often be shifted out of its normal position corresponding to a predetermined normal position of the core of operating solenoid. The result of this is that the accuracy of the meter is adversely affected, be-

cause, as is well understood by those skilled in the art, there is only a relatively small range of core positions of a solenoid which will give accurate operation when the device is used in a voltage regulating system.

In accordance with my invention I provide a novel contact making voltmeter in which the abov noted shortcomings of prior art voltmeters have been overcome.

An object of my invention is to provide a new and improved contact making voltmeter.

Another object of my invention is to provide a new, and improved arrangement for adjusting the stationary contacts of contact making voltmeters.

My invention will ,be better understood from 5 the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, in which like reference characters designate similar parts throughout the 1 several views, Fig. 1 isa perspective view of my contact making voltmeter; Fig. 2 is a partial, so-called, exploded view of certain of the elements of the meter; Fig. 3 is a part sectional view of the lower end of the operating magnet of my 5 meter, and Fig. 4 is a diagram showing the essential electrical connections of my meter.

Referring now to the drawing, it will be seen therefrom that my contact making voltmeter comprises a base member I on which is mounted go a main supporting member or casting 2, which serves, among numerous other things, to enclose the operating magnet 3 of the meter and the solenoid core 4 thereof. Member 2 may be made of any suitable material such as cast aluminum, 5 for example.'

As will be-seen more clearly in Fig. 3, the core 4 is provided with a stem 5 which passes through a guide member, or bearing 8, carried by the main casting 2. Guide bearing 6 may be con- 39 structed in any suitable manner, and for ample, it may comprise a glass bead.

. Casting 2 is also provided with an extension or bracket 1 which is integral therewith and which serves to support pivot bearing 8 for a 5 contact beam 9. The contact beam 9 is mechanically connected to the core 4 by means-of a resilient flat spring connection H], which serves to reduce any frequency vibrations of the core which would otherwise be transmitted to the so beam when the magnet is excited by alternating current but which acts to transmit greater move ments of the core produced by variations in the voltage of the circuit energizing the magnet 3.

From the above construction it will be seen 45 that the support for the magnet 3, the guide for maintaining proper alinement of the core of the magnet, and the support for the contact beam, are all one unitary structure with the result that it is practically impossible for these various parts 50 to get out of proper adjustment or alinement so that my meter is extremely rugged and reliable in operation.

Member 2 is also provided with an extension ll for supporting one end of a compensating spring l2 for supporting a part of the weight of the core I.

Also mounted on supportingextension, or arm, I is a unitary supporting member II for a pair of stationary contacts II and II for cooperation, respectively, with a pair of movable contacts I! and I! mounted on the contact beam 9. The member I3 is adiustably mounted on the arm I by means of a screw threaded connection consisting of a screw ll having screw threads engaged with threads in a threaded opening I! in the bracket I. The screw II has a flange 20 which is pressed tightly against the member II by means of a spring washer 2| which is interposed between the top of the member i3 and a knurled head 22 on the screw it. By means of the friction produced by the spring washer 2i between the flange 23 and the member II the adjustment of the member I3 is locked in any position in which it is placed.

For providing further accuracy of adjustment, a compression spring 23 is inserted in the threaded hole l3 and a ball 24 is placed in the bottom of this hole to reduce friction. By means of the compression spring 23 the screw threads of the members It and II are always pressed tightly against each other so that any lost motion therein is taken up at all times.

By means of this construction, turning the knurled head 22 raises and lowers the member i3, thereby simultaneously and equally raising and lowering the contacts I and It with respect to the contact beam 3. The result of this action is that the spread in voltage between the high value at which the contacts I I and I6 engage and the low value at which contacts I! and i1 engage, may be varied at will, while at the same time maintaining the same normal position of the contact beam for normal voltage intermediate these high and low values. This is of decided advantage because in previous meters, when the stationary contacts are separately adjustable, one of the contacts may be moved up or down more than the other so that during midvoltage conditions the contact beam will not be in its normal position, for example, the horizontal position, with the result that the core 3 will not be at the proper place in its travel to give maximum sensitivity of the device.

The tension of compensating spring I2 is made adjustable by means of a screw member 25 having a knurled nut 26 thereon, which is supported by means of a clamp member 21 on the extension i I. The jaws of the clamp member 21 are slightiy resilient and are pressed together so that the normal distance between them-is less than the thickness of the nut 28. Consequently, these laws press against nut 23 and the friction thereby produced serves to lock the adjustment of the nut 20.

Also mounted on the base member I are holding coils 28 which are enclosed in suitable casings 23 and which have threaded core members II whose positions are adjustable by means of knurled nuts II. The function of these holding coils, which is well known to those skilled in the art, is to attract the contact beam as soon as either set of contacts is in engagement, thereby causing a flrm positive engagement of these contacts and minimizing arcing and chattering thereof. As shown in Fig. 4, the holding coils are connected in series with the contacts of the meter, although they may be connected in any other suitable manner, such for example, as in paralaosaess lel, if desired. All of such connections are well known in the art.

Adjusting nuts 3| for the cores of the holding coils are locked in any given position by means of their special construction. This construction consists in providing these nuts with thin flanges 32 which are bent outwardly before the nuts are inserted in the spaces provided therefor in the casings 29. The bending of the flanges 32 is such that the overall width or thickness of the nuts is greater than the gaps in the casings provided for these nuts so that the friction produced by the flexing of these flanges serves to lock the nuts in any given position of adjustment.

For damping the motion of the core 4 I prois vide a special damping air vane construction comprising a vane 33, fastened to the end 1 of stem I, for sliding in the cylindrically formed lower portion of member 2.

For insuring proper alignment of the contacts, member i3 is provided with a pin 3| which normally flts relatively snugly in a slot 35 in projection I of casting 2 whereby member I3 is prevented from rotating.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modii'ications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. A contact making voltmeter including, in 85 combination, a contact beam, a pair of stationary contacts for cooperation with said contact beam, and means for simultaneously and equally adjusting the position of said contacts toward or away from said contact beam.

2. A contact making voltmeter having, in combination, a contact beam, a pivotal mounting for said beam, contacts carried by said beam on each side of said mounting, stationary contacts for cooperation with the contacts carried by said beam, and unitary means for simultaneously and equally adjusting the position of said stationary contacts toward or away from said beam carried contacts.

3. A contact making voltmeter having, in combination, a main supporting casting, a pair of stationary contacts, a member for carrying said contacts, screw threaded means for adjustably fastening said member to said casting, means for frictionally locking said screw in any position, and a spring cooperating with said screw threaded means for taking up any lost motion in the threads thereof.

4. A contact making voltmeter comprising, in combination, an operating magnet, a solenoid core therein, a stem on said core, a contact beam attached to said core, a main supporting casting enclosing said magnet, said casting being provided with a guide for said stem, said casting also being provided with a support for said contact beam, a pair of stationary contacts for cooperation with said beam, a member for carrying said stationary contacts in a substantially horizontal plane on opposite sides of said beam support, and means for adjustably positioning said member on said casting.

mm J. CHAMPLIN. 

